INVESTMENT IN SSAT (Details) - USD ($) $ in Millions		12 Months Ended
	Mar. 01, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Investments in affiliates
Investment in SSAT		$ 96.2	$ 84.1
Impairment charges related to investment in SSAT		0.0	0.0	$ 0.0
Operating lease right-of-use assets		369.6	357.7
Operating lease payments		148.2	148.7	154.3
Long-term operating lease liabilities		246.8	229.5
Financial information for equity method investment
Distributions received from SSAT		21.0	14.0
Current assets		471.9	609.6
Non-current assets		4,163.7	3,985.8
Total Assets		4,635.6	4,595.4
Current liabilities		527.4	560.4
Non-current liabilities		1,349.2	1,383.0
Total Liabilities and Shareholders' Equity		4,635.6	4,595.4
Company's share of income (loss) from SSAT		32.5	(1.0)	2.2
SSAT ST
Investments in affiliates
Ownership percentage, noncontrolling owner	50.00%
Ocean Transportation
Financial information for equity method investment
Company's share of income (loss) from SSAT		32.5	(1.0)	2.2
SSAT
Investments in affiliates
Increase in equity method investment in SSAT		13.2
Equity Method Investments, Increase (decrease) in deferred income taxes expense (benefit),		3.1
Equity method investments, increase (decrease) in retained earnings		10.1
SSAT | Ocean Transportation
Financial information for equity method investment
Current assets		271.0	305.7
Non-current assets		1,491.1	1,625.8
Total Assets		1,762.1	1,931.5
Current liabilities		269.1	271.9
Non-current liabilities		1,166.9	1,371.5
Equity		326.1	288.1
Total Liabilities and Shareholders' Equity		1,762.1	1,931.5
Operating revenue		1,274.0	1,193.3	1,025.1
Operating costs and expenses		(1,209.3)	(1,162.6)	(1,019.6)
Operating income		64.7	30.7	5.5
Net Income (Loss)		91.7	(6.4)	11.9
SSAT
Investments in affiliates
Asset impairment		0.0	18.4	0.0
SSAT | Ocean Transportation
Investments in affiliates
Cost of services from transactions with unconsolidated affiliate		341.9	320.9	$ 297.2
Accounts payable and accrued liabilities		40.5	34.4
Operating lease payments		0.4	0.4
Long-term operating lease liabilities		$ 0.8	$ 1.2
SSAT | SSAT ST
Investments in affiliates
Percentage of interests sold in SSAT ST	25.00%
SSAT's ownership interest in SSAT ST (as a percent)	50.00%